From the patent application FR 90 05240 there is known a three-phase electromagnetic motor including a rotor, having a preferably bipolar permanent magnet and a stator provided on the one hand with a peripheral stator portion forming a magnetic circuit of low magnetic reluctance and, on the other hand, a central stator portion formed to accommodate the rotor, such central stator portion being surrounded by the peripheral stator portion. Three coils mounted on three branches couple the central stator portion to the peripheral stator portion. The central stator portion exhibits three poles, each comprising a polar expansion partially surrounding the stator hole, the polar expansions being separated from one another by necks of high magnetic reluctance. The stator exhibits a planar structure located in a single common plane, the three branches including the three magnetic flux supplying coils being situated in a second plane parallel to the stator plane and neighbouring such plane.
Such three-phase motor of the star type presents the advantage of furnishing a non-zero average couple in successive supplying of the phases ("ON" phase sequence). However, it has the disadvantage of having a peripheral stator portion for the return of the magnetic flux. This structure necessitates a spreading out of the stator which renders the motor relatively cumbersome.
One of the purposes of the present invention is to overcome the disadvantage of this motor whilst maintaining the feeding and high yield advantages which it presents. Another purpose of the invention is to further improve the yield of such three-phase motor of the star type in increasing the magnetic coupling between the rotor and the magnetic flux supplying coils. Finally, it is sought to achieve these purposes whilst maintaining a relatively low manufacturing cost, that is to say, in providing an electromagnetic motor of simple construction and easy assembly.